Architecture for high power fiber laser

Abstract

A tapered fiber bundle (TFB) with a brightness reduction (R) that is between 0 and approximately 0.65 (or 65%), where R=(1−(d i /d a ) 2 ), d i is an ideal output diameter, and d a is an actual output diameter. The TFB is optically coupled to a gain fiber with a mode field diameter (MFD) that is between approximately 13 micrometers and approximately 25 micrometers.

What is claimed is: 
     
         1 . A system for operating in a single-mode regime, the system comprising:
 a gain-dopant being one selected from the group consisting of: Ytterbium (Yb); Erbium (Er); Thulium (Tm); Neodymium (Nd); Holmium (Ho); and combinations thereof;   a gain fiber comprising the gain-dopant, the gain fiber having a mode field diameter (MFD) between approximately 13 micrometers and approximately 25 micrometers, the gain fiber being one selected from the group consisting of: an amorphous silica fiber; and a crystalline fiber; and   a combiner optically coupled to the gain fiber, the combiner comprising an ideal output diameter (d i ), the combiner further comprising an actual output diameter (d a ), the combiner further comprising a brightness reduction (R=(1−(d i /d a ) 2 ), R being between 0 and approximately 0.65.   
     
     
         2 . The system of  claim 1 , R further being between approximately 0.2 and approximately 0.65. 
     
     
         3 . The system of  claim 2 , R further being between approximately 0.4 and approximately 0.65. 
     
     
         4 . The system of  claim 1 , the MFD further being between approximately 13 micrometers and approximately 18 micrometers. 
     
     
         5 . A system for operating in a single-mode regime, the system comprising:
 a gain-dopant;   a gain fiber comprising the gain-dopant, the gain fiber further having a mode field diameter (MFD) between approximately 13 micrometers and approximately 25 micrometers; and   a combiner optically coupled to the gain fiber, the combiner comprising an ideal output diameter (d i ), the combiner further comprising an actual output diameter (d a ), the combiner further comprising a brightness reduction (R=(1−(d i /d a ) 2 ), R being between 0 and approximately 0.65.   
     
     
         6 . The system of  claim 5 , further comprising:
 pump diodes optically coupled to the combiner, the pump diodes providing between approximately 50 Watts (W) and approximately 15 kiloWatts (kW) of pump power.   
     
     
         7 . The system of  claim 6 , each pump diode providing approximately 140 W of pump power, each pump diode having an operating wavelength of between approximately 900 nanometers (nm) to approximately 1020 nm. 
     
     
         8 . The system of  claim 5 , R further being between approximately 0.2 and approximately 0.65. 
     
     
         9 . The system of  claim 5 , R further being between approximately 0.4 and approximately 0.65. 
     
     
         10 . The system of  claim 5 , the MFD being between approximately 13 micrometers and approximately 18 micrometers. 
     
     
         11 . The system of  claim 5 , the gain fiber having a minimum bend radius of approximately 50 millimeters (mm). 
     
     
         12 . The system of  claim 5 , the gain fiber being a Ytterbium (Yb) doped fiber, the Yb-doped fiber having an operating wavelength between approximately 975 nanometers (nm) and approximately 1180 nm, the Yb-doped fiber further having a cutoff wavelength of approximately 1100 nm. 
     
     
         13 . The system of  claim 5 , the gain-dopant being one selected from the group consisting of: Ytterbium (Yb); Erbium (Er); Thulium (Tm); Neodymium (Nd); Holmium (Ho); and combinations thereof. 
     
     
         14 . The system of  claim 5 , the combiner comprising:
 inputs, each input comprising an outer diameter and a core diameter, the outer diameter being approximately 125 micrometers, the core diameter being approximately 110 micrometers; and   an output comprising an outside diameter, the outside diameter being approximately 250 micrometers.   
     
     
         15 . The system of  claim 5 , the combiner comprising:
 inputs, each input comprising an outer diameter and a core diameter, the outer diameter being approximately 125 micrometers, the core diameter being approximately 110 micrometers; and   an output comprising an outside diameter, the outside diameter being approximately 200 micrometers.   
     
     
         16 . A system for operating in a single-mode regime, the system comprising:
 a gain fiber comprising a gain-dopant, the gain fiber having a mode field diameter (MFD) between approximately 13 micrometers and approximately 25 micrometers; and   a combiner optically coupled to the gain fiber, the combiner further comprising a brightness reduction defined by R, wherein:
     R =(1−( d   i   /d   a ) 2 );
 
   d i  is an ideal output diameter; and   d a  is an actual output diameter.   
     
     
         17 . The system of  claim 16 , R being between approximately 0 and approximately 0.65. 
     
     
         18 . The system of  claim 16 , the MFD being between approximately 13 micrometers and approximately 18 micrometers. 
     
     
         19 . The system of  claim 16 , further comprising:
 pump diodes optically coupled to the combiner, the pump diodes providing between approximately 50 Watts (W) and approximately 15 kiloWatts (kW) of pump power.   
     
     
         20 . The system of  claim 16 , further comprising means for providing between approximately 50 Watts (W) and approximately 15 kiloWatts (kW) of pump power.